Indications
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Some experts advocate surgical resection for intramedullary spinal cord cavernous malformation only after progressive neurologic deterioration or for pain, which is often the presentation seen in adults. Others recommend surgical treatment after hemorrhage within the spinal cord, which is more commonly seen in children.
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Some neurosurgeons support early surgical intervention in symptomatic patients to halt neurologic decline.
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We recommend definitive surgical resection in all patients because untreated lesions may result in progressive neurologic decline. In addition, resection prevents potential hemorrhage, which carries with it a significant risk of neurologic compromise.
Contraindications
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Asymptomatic patients with incidental cavernous malformation can undergo serial magnetic resonance imaging (MRI) with close clinical follow-up to determine if and when surgical intervention is required. In these patients, the risk of hemorrhage versus surgical risk must be weighed.
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Patients with significant medical comorbidities that make undergoing surgery difficult can be closely monitored with serial imaging and clinical examinations.
Planning and positioning
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The initial assessment of a patient with a suspected intramedullary spinal cord cavernous malformation begins with a detailed history and physical examination.
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MRI of the entire neuraxis is necessary to diagnose additional spinal and intracranial lesions. MRI is also needed to localize the lesion and correlate with clinical findings. In addition, imaging is useful in planning the operative approach and helps predict deficits that may result from surgical resection. Cavernous malformations are usually occult to angiography and computed tomography (CT), so these imaging modalities are of limited benefit in presurgical planning.
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MRI typically reveals a hemosiderin ring that is characteristic of cavernous malformations. The lesion does not enhance with gadolinium, and there may be minimal spinal cord expansion.
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Waiting 4 to 6 weeks before surgery may benefit patients who present with an acute hemorrhage.
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Intraoperative neurophysiologic monitoring with motor evoked potentials (MEPs) is essential when operating on spinal cord cavernous malformations. Because many anesthetic agents cause depression of MEPs, the anesthetic regimen should be coordinated with the anesthesiologist before the start of the case. Propofol, fentanyl, and etomidate are commonly used agents that do not cause a decline in MEPs.
Figure 89-1:
Preoperative T2 sagittal and axial MRI showing an intramedullary cavernous malformation with a hemosiderin ring and slight expansion of the spinal cord.
Figure 89-2:
The patient is turned prone after intubation and all neurophysiologic monitoring electrodes are placed. For cervical lesions, the patient is pinned in three-point Mayfield head fixation and positioned prone on two chest rolls. The neck is slightly flexed to aid in surgical exposure. For patients with thoracic or lumbar lesions, prone positioning can be accomplished on a Wilson frame or chest rolls without head fixation. All dependent surfaces (e.g., knees, elbows) are padded to avoid peripheral nerve injury or pressure-related tissue necrosis.
Procedure
